1. Field of the Invention
The present invention generally relates to semiconductor devices and manufacturing methods of the same, and more specifically, to a semiconductor device packaged or forming a module by sealing a semiconductor element and a manufacturing method of the same.
2. Description of the Related Art
A solid-state image sensing device, formed by packaging and modularizing a solid-state image sensor with a transparent member such as glass, a wiring board, a wiring connecting the solid-state image sensor and the wiring board, sealing resin, and others, is well-known. Here, the solid-state image sensing device is, for example, an image sensor such as a Charge Couple Device (CCD), or Complementary Metal Oxide Semiconductor (CMOS).
FIG. 1 is a cross-sectional view of a related art solid-state image sensing device.
Referring to FIG. 1, a solid-state image sensing device 10 has a structure where a solid-state image sensor 8 is mounted on a wiring board 4 having a lower surface where plural bumps 2 are formed, via a die bonding member 6. A large number of micro lenses 9 are provided on an upper surface of the solid-state image sensor 8. The solid-state image sensor 8 is electrically connected to the wiring board 4 by a bonding wire 7.
In addition, a transparent member 1 such as glass is mounted above the solid-state image sensor 8 via a space 3. Parts of the solid-state image sensor 8 and the wiring board 4 where the bonding wires 7 are provided, external circumferential parts of the transparent member 1, and side parts of the spacers 3 are sealed by sealing resin 5.
Thus, the solid-state image sensor 8 is sealed by the transparent member 1 and the sealing resin 5. See Japan Laid-Open Patent Application Publications No. 62-67863, No 2000-323692, and No. 2002-16194.
However, coefficients of thermal expansion of members forming the solid-state image sensing device 10 shown in FIG. 1 are different from each other. For example, the coefficient of thermal expansion of silicon (Si) used as the solid-state image sensor 8 is 3×10−6/° C., the coefficient of thermal expansion of glass used as the transparent member 1 is 7×10−6/° C., the coefficient of thermal expansion of the sealing resin 5 is 8×10−6/° C., and the coefficient of thermal expansion of the wiring board 4 is 16×10−6/° C.
In addition, for example, the temperature inside of a reflow hearth in a reflow process for mounting a package such as a camera module on the wiring board 4 reaches around 260° C. Heat is applied as a reliability test of the solid-state image sensing device 10. Furthermore, in normal use of the solid-state image sensing device 10, the solid-state image sensing device 10 may be put under atmospheric conditions wherein the temperature in summer may be higher than 80° C.
Accordingly, under the atmospheric conditions wherein such a temperature change is made, the members may expand or contract by heat due to the difference of the coefficients of thermal expansion of the members, so that the transparent member 1 may receive stress from the sealing resin 5 and/or the wiring board 4. As a result of this, an interface of the transparent member 1 and the sealing resin 5, shown by a dotted line in FIG. 1, may peel off, or the transparent member 1 or the solid-state image sensing device 10 may be damaged.
Glass and others used as the transparent member 1 are strong against compression but weak (may be broken) against tension. Therefore, if the transparent member receives tension stress due to the difference of the coefficients of thermal expansion of the sealing resin 5 or the wiring board 4 and the transparent member 1, the transparent member 1 may be broken.
As discussed above, since the coefficient of thermal expansion of the wiring board 4 is greater than the coefficients of thermal expansion of the transparent member 1 and the sealing resin 5, the transparent member 1 and the sealing resin 5 may be pulled (tensioned) due to the thermal expansion of the wiring board 4. As a result of this, the transparent member 4 may be broken.
Because of this, a ceramic board having a smaller coefficient of thermal expansion may be used as the wiring board 4. However, the ceramic board is expensive and use of the ceramic board causes a high price of the solid-state image sensing device 10.
Similarly, in order to prevent the generation of the above-mentioned stress, the wiring board 4 may be formed by the same material as the transparent member 1 such as glass, and the solid-state image sensor 8 may be put between the transparent member 1 such as glass or the wiring board 4 made of glass, so that the members having the same coefficients of thermal expansion may be provided at upper and lower part of the solid-state image sensor 8. However, this structure is not preferable because the wiring board made of glass is also relatively expensive.
In addition, an air part is formed between the transparent member 1 and the solid-state image sensor 8 by the spacers 3 in the solid-state image sensing device 10 shown in FIG. 1. The air part contributes to a light condensing effect by the micro lens 9.
Japan Laid-Open Patent Application Publications No. 2003-197656 and No. 2003-163342 disclose a manufacturing method of the solid-state image sensing device having such an air part. However, in the above-mentioned manufacturing methods, it is necessary to prepare the spacer which fits to the size of the solid-state image sensor, namely a light receiving area. In addition, in the above-mentioned manufacturing methods, in a case where an anti-reflection film (AR coating film) for improving an optical property is provided on the transparent member, it is extremely difficult to form the spacer and a foreign article may become adhered to the transparent member.